Antibody-mediated targeting of uncoated (-mAb), Cetuximab- or Trastuzumab- coated Lm-spa+ after antibody crosslinking in xenografted mouse tumor models. In seven Balb/c SCID mice per group 4T1-HER2 tumors were induced and 14 days later the mice were infected with 1 × 108 CFU of differently coated Lm-spa+. 24 h later mice were sacrificed and tumors, liver and spleen excised aseptically. Tumors were digested with DNAse and Dispase to obtain single cell suspensions which were plated in serial dilutions without (a) and with gentamicin treatment (b) to determine total and intracellular bacterial counts, respectively. Depicted is the bacterial count per cell in the cell suspension. Liver (c) and spleen (d) were homogenized and plated in serial dilutions.